Exploder



Feb. 19, 1957 J, M. STQCKARD AL 2,781,724

EXPLODER 5 Sheets-Sheet 1 Filed Sept. 23'. 1948 Mm vvbvh a v INVENTORS JOHN M. STOCK/1RD STUART 6. MILLER wk E ink

ATTORNEY 1957 J. M. STOCKARD ETAL 2,781,724

EXPLODER 5 Sheets-Sheet 2 Filed Sept. 23, 1948 mvsmons JOHN M. STOGKARD STUART 6. MILLER.

ATTORNEY EXPLODER 5 Sheets-Sheet 5 J. M. sTocKARD ETAL Feb. 19, 1957 Fiied Sept. 25, 1948 R .s 9 6t mm m k ATTORNEY 1957 J. M. STOCKARD ETAL 2,781,724

EXPLODER 5 Sheets-Sheet 4 Filed Sept. 23, 1948 1957 J. M. STOCKARD E'I'AL 2,781,724

EXPLODER INVENTORS. JOHN M. STOGKARD STUART 0. MILLER 5 Sheets-Sheet 5 Filed Sept. '23, 1948 ATTORNEY EXPLODER John M. Stockard, Washington, D. C., and Stuart C. Miller, Silver Spring, Md.

Application September 23, 1948, Serial No. 50,726

24 Claims. (Cl. 102-17) (Granted under Title 35, U. S. Code (1952), see. 266) This invention pertains to torpedoes and, more particularly, is intended to detonate the warhead of a torpedo when it strikes its target, therefore being known as a contact exploder. While the instant disclosure of the invention confines the principles of the invention to underwater torpedoes such as are launched from submarine vessels, it is conceivable that those same principles would be just as elfective on a torpedo which could be launched into some fluid medium other than water.

In any case it is necessary that the exploder be kept inoperable until the torpedo has gone a sufiicient distance so that if, by some chance, the exploder should be cause to detonate the warhead prematurely, the force of the explosion will at least not damage the launching vessel. Therefore, in the conventional underwater torpedo to which type the specific description is now confined, and according to current practice, the exploder is armed by an im peller which is rotated as the torpedo travels through the water, and through a train of gears causes the expoder to be made ready to fire on impact against the target. This arming is effectuated only after the torpedo has traveled through the water for a predetermined and safe distance.

Because of the fact that despite known precautions premature explosions of torpedoes have occurred, the present invention provides in addition to a mechanical arming means as outlined, other and electrical means for arming the exploder. This electrical arming means comprises a depth safety switch and a distance safety switch, both of which serve to keep the electrical firing circuit open despite the possible closing of the inertia or firing switch until the torpedo has completed its arming run. Therefore the torpedo will not explode unless both the mechanical arming device and the electrical arming means perform their characteristic functions in serial order to establish the arming of the exploder.

With these premises in mind it can be understood that one of the objects of the invention is to provide a torpedo exploder in which mechanical arming and electrical arming are performed conjointly as a prerequisite to the firing of the torpedo.

Another object of the invention is to provide a torpedo exploder wherein there are a plurality of instrumentalities respectively dependent in their conjoint operation upon the preset distance traveled, the correct depth of submergence and the final impact of the torpedo against the target for the activation of the exploder to fire the terpedo.

Another object of the invention is to provide a torpedo exploder wherein mechanical arming is accomplished after an arming run of a preset distance, supplemented by the sequential closure of distance safety and depth safety electrical firing circuit vswitches, the closure of the firing circuit and the consequent firing of the torpedo being accompanied by the final closure of said circuit upon impact of the torpedo against the target.

A further object of the invention is to provide a torpedo exploder embodying a discardable impeller, the abice sence of which at the time of impact increases the firing sensitivity of the torpedo.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is an inverted longitudinal section of one form of the torpedo exploder, constructed in accordance with the principles of the invention;

Fig. 2 is a perspective view of the exploder, some of the structure being omitted for the sake of clarity;

'Fig. 3 is a perspective view of the gear train for transmitting motion from the impeller to the arming ring;

Fig. 4 is a vertical cross section taken on line 4-4 of Fig. 1;

Fig. 5 is a vertical cross section taken on line 5-5 of Fig. 1;

Fig. 6 is a vertical cross section taken on line 6-6 of Fig. 1;

Fig. 7 is a vertical cross section taken on line 7-7 of Fig. 1;

Fig. 8 is a vertical section taken on line 8-8 of Fig. 1;

Fig. 9 is a vertical cross section taken on line 9-9 of Fig. 1;

Fig. 10 is a detail vertical cross section taken on line 10-10 of Fig. 5;

Fig. 11 is a detail horizontal section taken on line 11-11 of Fig. 2;

Fig. 12 is a diagram of the electrical wiring for the exploder, particularly illustrating the three switches;

Fig. 13 is a perspective view of a modification of the exploder, parts being shown in section;

Fig. 14 is a longitudinal section taken on line 14-14 of Fig. 13;

Fig. 15 is a perspective view of the setting shaft and dial disk appearing in Fig. 13;

Fig. 16 is a detail perspective view of the dial disk;

Fig. 17 is a cross section taken on line 17-17 of Fig. 14;

Fig. 18 is a cross section taken on line 18-18 of Fig. 14;

Fig. 19 is a cross section taken on line 19-19 of Fig. 14;

Fig. 20 is a cross section taken on line 20-20 of Fig. 14;

Fig. 21 is a partially sectional and elevational view to V be identified with Fig. 14, illustrating the action of discarding the impeller, and

Fig. 22 is a detail elevation of a portion of the impeller expelling mechanism, a part being shown in section.

The invention will first be described generally with particular attention to the wiring diagram of Figure 12. An exploder 11 is positioned ina suitable well in the nose of a torpedo. An impeller shaft 12 is rotated by the travel of the torpedo through the water to mechanically arm two cannon primers 13 and 14; that is, a metal shutter is so moved that either of the primers 13 and 14, when fired on impact, is efiective, in conjunction with other instru-v mentalities, to detonate the main explosive charge of the warhead. Rotation of the impeller shaft 12 will, in addition to mechanically arming the primers 13 and 14, throw a distance :switch 15 to electrically arm the same primers 13 and 14; that is, after a predetermined travel of the torpedo through the water, the switch 15 will be closed. Another switch 16 is in the electrical circuit between the distance switch 15 and the primers 13 and 14. This switch 16 is hydrostatically operated to close when the torpedo has ascended above a critical depth. The purpose of the depth safety switch 16 is to prevent explosion of the warhead while the torpedo is below this critical depth (above which the submarine need not ascend until o the terp'edo has finished i'tsrun). The circuit also incorporates a firing switch 1'7 that is operated by inertia. Impact of the torpedo against its target will allow the inertia switch 17 to complete theelectric-al firing circuit and thereby toignite the primers 1 3 and 14. While two primers 13 and 14 are shown, it is realized that one or three many other number may be used instead.

It will be se en,theref ore, that in accordance with the principles of the invention, this torpedo exploder comprises four safety features:

1) A mechanical arming device for the cannon primers 13 and 14. i V

(2) An electrical distance safety switch 15 for electrically arming the same primers.

(3 An electrical hydrostatic or depth safety switch 16.

(4;) An electrical inertia or firing switch 17.

p All four of these safety features must be operative or closed conjointly before the warhead can be detonated.

The form of the invention illustrated in Figs. 1 through 11 is now described in detail. The exploder 11 comprises a gear case21 in the fore position and a shutter housing 22 in the aft position. These members are spaced from each other and joined together by a plurality of tie rods 23, here shown as comprising three members. One reduced end of each tie rod 23 is screwed into the gear case 21, the other reduced and terminally threaded end extending through a hole in the shutter housing 22. A nut 24 and a washer 25 tighten the shutter housing against the shouldered tie rods in fixed spaced relation to the gear case 21. The shutter housing 22 has a central cylindrical chamber 26 extending rearwardly to contain a booster charge 27 of tetryl 'or the like.

Placed over the end of the chamber 26 is a can 28 containing an auxiliary booster 29 that is adapted to explode the main charge of the warhead. The foregoing assembly and other parts to be described occupy a casing 30, into the forward and initially open end of which the assembly is' inserted. The casing 30 is the previously mentioned well, and it is embedded in the explosive substance (not shown) of the warhead later again identified as 54.

E'ccentrically recessed within the shutter housing 22 is a rotatable cylindrical shutter 31. A shutter shaft 32 passes through a Wall portion 21a of'the gear case 21 and theaxis of the shutter 31 which is fastened to said shaft. The shutter shaft 32 is driven from the impeller shaft 12 by a step-down gear train (Fig. 3) presently more fully described.

The two electric-firing primers 13 and 14 (Fig. 2) are positioned in appropriate radial apertures (Fig. 9) in the shutter housing 22. The cylindrical surface of the shutter housing 22 is cut away to form fiat portions against which the heads bear when the primers 1'3 and 14 are screwed home so that said heads do not project above the cylindrical surface of the shutter housing 22. The axes of the primers 13 and 14 are arranged to intersect near the cylindrical surface of the head of the Shutter 31 (Fig. 9), so as to provide a single firing orifice through which both primers can fire into the shutter recess 31a. The shutter 31 has a radial aperture 33 and a connecting aperture 34, the latter aperture '34 being parallel with the axis of the shutter 31. The apertures 33 and 34 form a right angle passageway extending from the cylindrical surface of the shutter 31 to the aft base thereof. 7

The construction ofthe apertures 33 and 34 is such that upon rotation of the shutter shaft 32 and the shutter 31 through a limited angular distance the radial aperture 33 will at one point in its travel come into alignment with the firing orifice of the primers 13 and 14 in the shutter housing 22. This position of the shutter 31 is called the armed or firing position. When loaded, the apertures 33 and 34 contain a fuzing charge such as lead azide pellets. So loaded, the apertures 33 and 34 constitute an explosive train to communicate the detonation of primers 13 and'14.

When the detonator is armed, that is, when the outer end of the aperture 33 is opposite the firing orifice of primers 13 and 14 in the shutter housing 22 the aperture 34 will come into registration with a stationary port 36 (Fig. l) in the'shutter housing 22. This port 36, when loaded, also contains a fuzing charge such as lead azide pellet and leads to the chamber 26 that contains the booster 27. It will be seen, therefore, that when the shutter 31 has been rotated to its firing position, ignition of the primers 13 and 14 will ignite the fuzing charges in the passageways 33, 34,- and 35, and that the explosion of the primers 13 and 14 will be communicated to the booster 27, in turn to the auxiliary booster 29, and by that booster to the main explosive charge of the torpedo.

To retain the shutter 31 in axial position relative to the shutter housing .22 there is provided a shutter retainer 37. The retainer 37 has a center bore large enough to clear the shutter shaft 32 which extends through it. The shutter retainer 37 is secured to the shutter housing 22 by screws (Figs. 8 and 13) or other suitable fastening means.

The shutter 31 has a segment cut away at 38 (Figs. 6, 8 and 9) to provide a gas escape vent. In the unarmed posit-ion of the shutter 31,- the vent 33 will be adjacent the primers 13 and 14 (Fig, 9), so that if a premature ignition of the primers 13 and 14 should occur the flame and gaseons products will expand through the vent 38 into the space S (Fig. 1) between the gear case 21 and the shutter housing 22 (Pig. 1) without firing the fuze trains 33, 34, 36 or the booster 27. The main body of the shutter 31 will bar passage of the explosion to the detonator in the apertures 33 and 34. Since the circular body portion of the shutter retainer 3? has an external diameter slightly smaller than that of the shutter recess (Fig. 8) the flame of a premature explosion of the primers 13 and 14 will have an adequate outlet from the vent 38 into the casing space.

A varied impeller 41 which is the prime mover of the arming mechanism is mounted on the front end of the shaft 12. This shaft is of a desired fragility so that it will break upon impact of the impeller with the target. The rear portion of the shaft has a worm 42 formed on it, the Worm being in mesh with a wormwheel 43 to drive it. On the same shaft 39 with the wormwheel 43 is a second worm 44 (Fig. '3) that meshes with another wormwheel 45 fixed on a shaft 46 parallel to the impeller shaft 12. Fixed on the shaft45 is a pinion 47 that meshes with a gear 48 pinned on the shutter shaft 32. It will be understood, therefore, that rotation of the impeller 41 will, through the gear train 42, 43, 44, '45, 46, 47, and 48, drive the shutter shaft 32 to rotate the shutter 31 into the desired arming position Thesegears, the shutter shaft 32 and the shutter 31 thus become instrumen'talities which operate as a register of the distance traveled in the safety run of the torpedo. The gear case 21 has a forward extension 49 to serve as a journal for the impeller shaft 12.

It is to be noted at this point that the entire gear train (Fig. 3) between the impeller shaft 12 and the shutter shaft 32 is in a chamber open to the sea. This circumstance is a concession to the relative torques of the shafts 12 and 32. The shaft 12 which is rotated at the highest rate of any shaft has the lightest torque of any shaft and for that reason would demand a critical adjustment of a packing gland if it wasrequired to provide for watertightening the gear case. The least variation in the compression of the packing gland would alter the rate of rotation of the impeller shaft and therefore the effective safety run of the torpedo. on the other hand, the shutter shaft which is geared down to only a fraction of a revolution during the safety run rotates with the heaviest torque. Consequently the packing gland 35 (Fig. l) is placed where the stuffing box friction will have the least critical effect. in other words, it is the shutter shaft that is made to rotate in the stuffing box where any variation of the tightening of the gland nut, within a reasonable range, will not impose a brake behind the gear train and so unpredictably increase the safety run of the torpedo.

The gear case 21 is provided with a central circular flange 51. A cover nut 52 of cylindrical form is adapted to enclose that portion of the exploder between the impeller 41 and the flange 51 of the gear case 21. The cover nut abuts the flange 51 and is externally threaded at 53 so that it may be screwed into the nose 54 of the torpedo warhead.

The cover nut 52 has two diametrically opposite holes 55 at its front end. In line with these holes 55, the impeller shaft 12 has a lateral aperture 56 passing through the center thereof. The gear case extension 4? also has a hole 60 (Fig. 2) in registration with the holes 55 and the aperture 56. A locking safety wire 57 is passed through the holes 55, the aperture 56, and the hole 60. The purpose of the locking safety wire 57 is to prevent rotation of the impeller shaft 12 until the torpedo is prepared for launching at which time the locking safety wire 57 is removed.

An additional safety feature is provided by means of a safety arming wire 58 that is inserted through an aperture 59 in the impeller shaft 12. This wire 58 is applied only when the locking safety wire 57 is removed as the torpedo is prepared for launching; The front or nose end of the cover nut 52 has a boss 61 that has several pairs of aligned radial apertures 62 (Fig. 4) and at the proper time the arming wire 58 is passed through a pair of these apertures 62 and through the aperture 59 in the impeller shaft 12. A helical spring 63 is positioned about the impeller shaft 12 between a washer 64 and a collar 65, both of which also surround the impeller shaft 12. The collar 65 has a circular flange 66.

A pair of partly threaded set screws 67 'is driven through suitable apertures in the boss 61 of the cover nut 52, and the smooth ends of the set screws, in the unarmed position of the exploder, provide backings for the flange 66 of the collar 65, keeping that collar clear of the holes 62. Before the torpedo is launched the safety arming wire 58 is inserted through one of the pairs of holes 62 and through the aperture 59 in the impeller shaft 12. Thereafter the set screws 67 are unscrewed and withdrawn from the boss 61 of the cover nut 52. The helical coil spring 63 which has been under compression will be partially released and will force the collar 65 forwardlly, that is, toward the impeller 41.

The aperture 59 in the impeller shaft 12 is so positioned that the expansion of the spring 63 will urge the collar into frictional contact with the safety arming wire 58 in the aperture 59. The friction will be sufficient to prevent accidental dislodgment of. the safety arming wire 58. When the torpedo is placed in the torpedo t-ube, one end of the safety arming wire 58 is anchored to a portion of the torpedo tube or other relatively fixed member, so that launching of the torpedo will cause the end of the safety arming wire 58 to be withdrawn from the exploder. After the safety arming wire 58 has been so withdrawn, the motion of the torpedo through the water will cause rotation of the impeller 41.

The cover nut 52 has a series of large equally spaced apertures 68 around its circumference at its midportion in order to permit the use of a spanner wrench to tighten the cover nut 52 in the nose 54 of the torpedo. It is through these apertures and through the holes 55 that sea water enters the gear chamber.

The impeller shaft 12 is heldagainst longitudinal dislodgment by means of a lateral pin 69 which passes through a hole 70 (Fig. 2) in the forward extension 49 of the gear case 21 and crosses a reduced portion 60a of the shaft 12. If the pin 69 is removed, the impeller shaft 12 may with a little manipulation be retracted from meshing engagement with the wormwheel 43 and may be with drawn entirely from the body of the exploder 11.

The shutter shaft 32 carries a cam collar 71 (Figs. 1, 6 and 12) near its forward end. This collar is flattened at 40. Said collar obstructs the operating button of the distance switch 15, resisting the effort ofthe button to move out and thus hold the switch normally open. After the shutter shaft 32 hasrotated 180 (Fig. 6)'according to the present setting, the flat place 40 makes room for the movement of the switch button which, upon projection, permits closure of the distance switch. Theclosing of the switch 15, which constitutes the electrical arming of the exploder, will coincide substantially with the mechanical arming thereof by means of the shutter 31.

Both of these steps are etfectuated by the rotation of the shutter shaft 32, and the amount of that rotation, which is provided by roation of the impeller 41, can be varied manually so as to effect the arming after any desired extent of travel of the torpedo through the water,

up to the mechanical limitation of the mechanism. The latter factor, however, can be altered by changing the gear ratio of the impeller pitch.

The depth switch 16 includes a housing (Fig. 10) which consists of two parts. One part 87 which is cylindrical is essentially integral with the gear case 21, having a force, shrink or sweat fit therein. It provides a chamber, open to seawater pressure, to contain the hydrostatic elements of the switch, namely a plunger 74 and bellows 88. The other part 72 of the switch which is irregular in shape fits over the cylindrical part 87 and is secured to the gear case 21 by means of bolts 73 or the like. It carries the electrical element 16 and the connection jack 75. This jack is mounted at the end of the depth switch housing 72 and is for the purpose of making rapid and easy electrical connection of the exploder circuit to current source B (-Fig 12) elsewhere in the torpedo.

Since the outside of the bellows 88 (-Fig. 10) is exposed to seawater (Fig. 2), the interior of the cover nut 52 being accessible to the seawater as has been explained, hydrostatic pressure will push the plunger 74 in to open the electrical switch. Said switch will be moved to and retained in the open position whenever the depth of 'submergence of the torpedo and the consequent hydraulic head is great enough to overcome the combined resistance of the bellows 88 and the operating spring inside of the switch 16.

These resistances are calibrated to insure opening of the switch 16 at the desired and predetermined depth. Thus the depth switch 16 is held open by hydrostatic pressure at the depth of water at which the torpedo is launched from the submerged submarine vessel. When the torpedo has ascended, in approaching the surface to reach its target, to a depth above which it is not intended to bring the firing submarine until the torpedo has completed its run, the decrease in hydrostatic pressure will permit the plunger 74 to move forwardly (to the left in Fig. 10). This allows the depth switch 16 to close, and that is one of the prerequisites for firing the exploder.

The gear 48 is slotted through at 79 (Fig. 5). It is also marked with graduated indicia which are stepped away from the slot at distances agreeing with contemplated arming travels of the shutter shaft 32. Suppose, for example, that the safe arming distance is determined to be 300 yards. The gear 48 is set, prior to making the gear train assembly and, obviously, before emplacing the cover nut 52, with the inscribed 300 yard mark 76 (Fig. 5) in registration with what will be the center of the impeller shaft 12 when the assembly is completed. The gear 48 must then rotate the 180 distance indicated before the slot 79 coincides fully with the end of the impeller shaft 12. If the contemplated run was the improbably used but possible distance of only 50 yards, that graduation would have been registered with the expected impeller shaft center, whereupon the gear 48 would need to rotate only a short distance before the slot admitted the end of the impeller shaft.

Until this position of registration is reached the face of the gear 48 provides a bearing for the inner end of the shaft 12 and to resist the end thrust of the worm 42.

'This end thrust is engendered in part by the resistance of the water ahead of the impeller during the forward motion of the torpedo and inpart by frictional resistance of the subsequent gear train,- a portion of which is deliberately imposed through the inst-rumentality of helical spring 77, as described hereinafter. When this bearing surface is removed, as when the slot 79 registers fully with the end of the impeller shaft, the rearward thrust of the worm 42 responding to the external end thrust of the fluid on the impeller will push the end of the impeller shaft through the slot. When this happens the worm 42 will no longer be in engagement with the wormwheel 43. The reduced portion 60 is long enough to provide the necessary end motion. Subsequent movement of the torpedo through the water will continue to rotate the impeller and the impeller shaft, but the train of gears ceases operation and the gear 48 is positively locked against further rotation by the engagement of the impeller shaft end with the slot 79. The shutter 31 will have been turned (Fig. 9) to-register the cannon primers 13 and 14 with the port 36. The distance switch 15 (Figs. 6 and 7) will have closed.

A helical spring 77, contained by a'housing 73 (Fig. 5')

which is secured to the gear case extension 49, pushes a friction disk 80 against the wormgear 43. These provisions impose a frictional drag on the wormwheel 43 set up'by the spring 77, which has the effect of increasing the end thrust of the worm 42. This efiect insures that the keeping the wormwheel 45 and the shaft 46 properly supported and centered. The bearing plate 81 has a central spherical knob 82 that is adapted to contact the central portion of the wormwheel 45 and to act as a bearing therefor. The plate 81 is fastened to a bracket 83 (Fig.

2) on the gear case 21 by means of two screws 84 that pass through suitable spacers 85.

The inertia switch 17 is positioned longitudinally of the exploder 11 (Fig. 2) and the plunger 89 (Fig. 11) thereof is parallel to the axis of the exploder. Within a casing 91 is a heavy conical member 92 that has a base a and constitutes the inertia element. The casing has an abutment which is confronted by the inertia member. The inertia element 92 is centrally apertured to contain a movable piston 93. The piston 93 is threaded to mesh with an appropriately threaded portion of the inertia element 92, and the forward end has a screwdriver slot 94 to permit adjustment of the position of the piston 93 within the inertia element 92. The rear portion of the piston 93 is adapted to contact the plunger 89 of the switch 17, here shown as a micro switch, that constitutes the firing element of the electrical circuit. The inertia element 92 is spring pressed toward the rear so that its base bears on the casing abutment, by a helical spring 97 that thrusts against the rear portion or base of the inertia element 92 and against a sleeve 98 that is held within the casing 91 by a snap ring 99.

The switch 17 is normally, by itself, in closed position; that is, when there is 'no pressure against the movable plunger 89, the switch is closed. When assembled within the casing 91, the plunger 89 is spring pressed toward the rear by the piston 93, impelled by the spring 97, so that the switch 17 is held open. When the torpedo strikes its target, the inertia of the heavy member 92 will cause it to continue in a forward direction, or, if the major component of impact is normal to the torpedo axis, to wobble between the base and abutment, and the pressure on the movable plunger 89 will be relieved, allowing the switch 17 to restore itself to closed position, and thereby to complete the electric firing circuit and explode the warhead.

The operation of the exploder is now described. Before {the exploder 11 is inserted into its casing 30 in the torpedo, the arming distance ;is;set;manu'ally, by rotating the shutter shaft .32 :to' register the desired sc-riber mark such as 76 (Fig. 5), with what will be the axis of the shutter shaft when-the assenihlyis completed. The safety Wire 57 is removed, and theflarming wire .58 is inserted through the appropriate apertures 62 {in the covernut;5,2 and through the hole 59 in the impeller shaft 12; The screws 67 are thenremoved,-so that the spring 63 pushes the collar 65 against the arming wire 58. The electric firing circuit of theexploder is connected to the current source B by means of the jack 75. The explodcr is inserted into the cavity ;in the nose 54 of the torpedo, and one end of the arming wire 55S is anchored to a fixture.

When the torpedo is launched, the arming Wire 58 will be withdrawn from the explodcr, with the result .that rotation of the impeller 41 as the torpedo travels through the water,- will ,set its associated mechanisms into operation in the manner detailed before. By the time the shutter shaft 32 has rotated through-an angular distance sufiiciently large to register the slot 79 (Fig. 5) with the inner end of the'shutter shaft (Fig. 1), the torpedo will have traveled asufiicient distance so that its explosion thereafter would not normally injure the firing ship. The shutter 31 (Fig. 9) will then be in position to establish communication between the passageway 33, 34 (Fig. 9) and the common orifice of the cannon primers 13, 14 with the port 36. At the same time the flat'place 40 of the cam collar '71 will have come opposite to the plunger of the switch 15, permitting that plunger to move out and thus close the distance switch. The mechanical and electrical arming of the exploder is thereby simultaneously accomplished.

The exploder is locked in the foregoing armed position by the projection of the impeller shaft end into the then registering slot 79, the shaft being impelled to make the requisite rearward -,movement by the external fiuid end thrust against the impeller and by the thrust imposed on the shaft 12 at the worm 42. The latter is simultaneously released from meshing engagement with the wormgcar 43 so that thenceforth further rotation of the impeller 41 and of the shaft '12 will be idle and ineffectual in producing any change in the armed status of the mechanism until the torpedo str-ikesthe target.

When the torpedo strikes the target, its negative acceloration causes the inertia element 92 (Fig. 11) to leave its seat in casing 91 by virtue of its own momentum, releasing pressure ofits piston 93 from the plunger 89 of the inertia switch 17. That switch will close and, provided the torpedo is above a predetermined depth, the torpedo will be exploded. If the torpedo is below that depth, the depth switch 16 will remain open and prevent the explosion.

Attention is next directed to the second form of the invention shown in Figs. 13 through 22. In this species the cannon primers 13, '14, inertia switch 17, shutter 31 (Fig. l3) and their associated mechanisms are similar in structure and operation to those described with respect to the first form of the invention. The structure and mechanism inside and in front of the gear case is different, for the purpose of providing means whereby the arming impeller 41 with its shaft 111 are automatically ejected and discarded as soon as the impeller has caused the exploder to be completely armed. An advantage of using the discardable impeller is the ability to leave it off in the preliminary handling of the torpedo, thus avoiding the breaking .of the shaft vwhich, in the first form, is fragile.

The reasons which make such elimination of the impeller after it has completed its arming function desirable are: 1) In the first form of the invention, if the torpedo strikes so that the impeller comes first into contactwith the target, a portion of the energy of impact is absorbed in crushing the impeller, and breaking its fragile shaft, thus diminishing the sensitivity of the exploder objectionably, and: ('2) Should the enemy recover an unexploded torpedo equipped with an armed exploder, in which condition it would be extremely hazardous to handle or disexploder were of the form of invention first described where the impeller is retained after sewing its purpose, for the enemy to disarm the exploder by pulling the impeller outward so as to reengage the arming gear train and rotating it a number of turns in either direction.

The impeller 41 has a hub 111 with a pinion formed by a toothed annulus 112 extending rearwardly therefrom. Beyond the toothed annulus 112 is a groove 113 forming a reduced neck and a collar 114. The neck is part of a stub impeller shaft which is retained in a bore in the hub of impeller 41 by the pin 69 which crosses a reduced portion of the shaft. The stub shaft is adapted to be held while the impeller rotates freely in reference to it. A gear case 115 similar tothe gear case 21 contains a train of gears for transmitting rotary motion from the impeller shaft 111 to the shutter shaft 32 (Figs. 14 and 21) and to the other mechanisms for arming and firing the exploder. When the impeller 41 is in its operable position, the toothed annulus 112 engages the teeth of a spur gear 116 (Fig. 17). The gear 116 meshes with another gear 117 in the same plane. The gear 117 is fixed on a shaft 118 that carries a cam 119 (Figs. 18 and 19). A yoke 121 (Figs. 13 and 19) rides on the cam 119 and is pressed by a coil spring 122 which is supported by a bracket 123, against the cam 119 to resist rotation of the gear train other than by rotation of the impeller 41 by the travel of the torpedo through the water.

The spur gear 116 is loosely carried on the front end of a shaft 124, to the rear end of which is secured a pinion 126. The gear 126 drives a gear train (Fig. 20) comprising gears 127, 128, 129, 130, 131, 132, and 133. The gear 133 meshes with a gear 134 equivalent to gear 48, that is secured on the shutter shaft 32. It will be understood, therefore, that when the impeller 41 is in its working position, rotation thereof will act to rotate the shutter shaft 32 to'mechanically and electrically arm the exploder as in the first form of the invention.

The gears 126 through 134 are backed by a gear plate 136 that has an arcuate cutout portion 137 (Fig. 20) to facilitate assembly. The gear plate 136 is spaced from the bottom or inner end of the gear housing 115 by a plurality of tubular spacers 138 through each of which a fastening screw 139 passes to secure the gear housing 115 to a base plate 141 (Fig; 13). The base plate 141 has an annular flange 142 against which is fitted the end of a cylindrical cover nut 143 to substantially enclose and protect the gears as in the previous species.

The exploder as illustrated by Figs. 13 to 22 is shown as fitting entirely within the outline of the torpedo, as distinguished from the first form. This, however, is not essential or may apply to either form.

The impeller discarding means of the second form of the invention will now be described. The gear case 115 is chambered centrally at 151 to hold a cylindrical sleeve 152 that contains two helical springs 153. The sleeve 152 has a reduced forward portion 154 that would project through a central opening 155 in the gear housing 115 under action of the springs 153 is permitted. A transverse slide member 156 (Figs. 18 and 22) is provided with two circular openings 157 and 158, each of which is large enough to permit passage therethrough of the reduced forward portion 154 of the sleeve member 152. The apertures 157 and 158 are joined by a lateral slot 159, the width of whichis sufiicient to accommodate the neck 113 but smaller than the identical diameters of the collar 114 and the reduced central portion 154 of the sleeve 152. The forward section of the gear housing 115 has a lateral groove 161 (Fig. 18) in which the slide 156 may move back and forth.

The gear housing 115 contains adongitudinal shaft 162 parallel with the axis of the sleeve 152 and with the axis of the shutter shaft32. A helical spring 163 bears against a collar 164 fixed on the shaft 162. V The rear end of the spring 163 bears against a constriction 165in-the gear housing 115 in whichconstriction the shaft 162,has"bearing, so that normally the spring163 urges the shaft 162 in a forward direction. The gear 133 (Fig. 14) that meshes with the shutter gear 134 is fixed on the rear end of the shaft 162 in such a manner that when the shaft 162 is in its forward position under action of the spring 163, the gear 133 will also mesh with the gear 132. There is suflicient space to allow the shaft 162 rearward movement against the force of the spring 163 to disengage the gear 133 from the gear 132 while remaining in mesh with the shutter gear 134 at all times. The slide 156 has rack teeth 167 (Figs. 18 and 22) along one side thereof that are engaged with a pinion 168 out on the front end of the shaft 162.

Forward of the pinion 168 is an overhanging dial disk 169 (Fig. 15). The front end 171 of the shaft 162 is squared to form a nut so that a suitable wrench may be used to rotate the shaft 162. The gear 116 (Figs. 14 and 17) overlaps the slide 156, with the result that the slide 156 is held against appreciable forward movement on the neck 113. The curved openings 157 and 158 in the slide 156 are large enough to let the collar 114 through as a requisite to discarding the impeller. The slot 159 in the slide 156 is too small to admit the collar 114, hence locks the impeller against coming off as long as the slide position in Fig. 18 is maintained. When the position in Fig. 22 is reached the portion 154 obstructs the slide from further movement in either direction, hence locks the gear train.

The setting and detailed operation of the impeller-discarding mechanism are as follows. The exploder comes as a separate unit to be inserted into the nose of the torpedo. A pin 172 (Fig. 14) is slid into a slot 173 in the inner wall of the well 137 to prevent turning of the exploder in the well. The initially separate impeller 41 is attached to the exploder by inserting the hub 111 into the opening 155. The sleeve portion 154, appearing at the mouth of the opening, is pressed inwardly by pushing the collar 114 against it and past the slide 156, the opening 157 (Fig. 18) of which slide was occupied by the portion 154 up to this time. A wrench now applied to the nut 171 is pushed in. and at the same time turned clockwise (Fig. 17) just far enough to displace the slide a little to the left by action of the pinion 168 on the rack 167. This causes the slot 159 to ride onto the neck 113, and since the slide now obstructs the collar 114 the impeller is held on until the opening 158 is eventually brought into registration with the collar.

Setting for distance is next accomplished by continuing the foregoing pushing and turning of the wrench. The pushing disengages the gear 133 from the pinion 132 (Fig. 20) of the gear train behind it, and the turning registers the desired indicia 76 on the dial 169 with the reference mark 174 on the front cover 175 of the gear case. That indicia is calibrated to read either as shown in Figs. 5 or 17, depending upon the originally intended range of the torpedo. The ISO-yard range denoted in Fig. 17 is not a limitation upon the inherent mechanism, since by altering the ratio of the gear train the range can be increased to the extent shown in Fig. 16 or what is denoted in Pig. 5. The dial 169 (Fig. 15) includes the letters S and A, standing for safe and armed. As long as the opening 157 coincides with the axis of the exploder the dial reading will be safe. The shutter 31 (Fig. 13) then stands in a position agreeing with Fig. 9.

Assuming that the ISO-yard range is selected for the firing of the torpedo, the foregoing turning of the wrench needs to be only a slight amount clockwise to register the ISO-yard indicia 76 with the mark 174. Removal of the wrench and the inward push exerted through it permits the i e-engagement of the gear 133 with the pinion 132 of the gear train.

'Upon launching the torpedo spinning of the impeller 41 begins due to the movement of the torpedo through the water. The impeller drives the gear train (Fig. 20), and after the propeller has made a determinable number of rotations the slide 156 will have been moved leftward -rence the cam will soon ride up under the spring-biased yoke 121 (Fig. 19) which from there on will resist any further casual turning of the impeller.

The cam 119 and spring-biased yoke 121 thus constitute a brake, and in addition to checking casual turning of the impeller the brake imposes a drag on the impeller in the initial stage of launching, preventing the impeller from revolvinguntil the torpedo speed reaches approximately twelve knots. Thereupon the brake will be overcome and the gear train will operate to bring the opening 158 into registration with the axis exploder.

There is thus an analogy between the arming wire 58 of the firstform of the-exploder and the brake 119, 121 of the second form. Each is intended to keep the impeller from revolving prior to launching. In the first form the braking effect of the arming Wire ends simultaneously with launching, but in the second form the braking eifect endures until a predetermined speed is reached.

As the opening 158 is brought into registration with the axis of the exploder the springs 153 (Fig. 14) will be free to act through the sleeve 152 and its reduced portion 154 to push the hub 111 out of the opening 155 and thereby eject the shaft and discard the impeller from the exploder (Fig. 21). The gear train then becomes dormant and by this time the shutter 31 (Fig. 13) will he in that position wherein its passageway 33, 34 (Fig.9) containing the detonating pellets will. be in communication with the common orifice of the cannon primers 13, 14. The presence of the portion 154 in the opening 158 (Fig. 22) locks the gear train against any further motion. The mechanical arming of the exploder is then complete, just as in the case of the first form of the invention.

Simultaneously with this occurrence the cam 71 on the shutter shaft 32 (Fig. 14) will have closed the distance switch 15 in the manner previously described for the first form of the invention. Two switches-remain to be closed. The depth switch '16 (Fig. 13) remainsopen as long as the torpedo stays below a critical depth being held so by seawater admitted to the cylinder 87 and to the end of the bellows 88 (Fig. 14)'through the-aperture 146. When the torpedo has ascended above this critical depth the diminution of pressure will permit the switch 16 to close again just as in the first form of theinvention.

The inertia switch 17 (Fig. 13) is last to close. This closure occurs upon impact of the torpedo against the target, and the operation thereof upon impact is precisely as already described. The resulting detonation of the cannon primers 13, 14 ignites the pellets in the passageway 33, 34, the powder train being traced through the boosters 27 and 29 (Fig. 1) to the main explosive charge of the warhead, all as in the case of the first form of the invention.

Obviously many modifications and variations of the present invention are possible .in the light of the above teachings. It is therefore to be'understood that Within the scope of the appendedclaims the inventionmay be practiced otherwise than as specifically described.

The invention described herein-may be manufactured and used by or for the Government'of the United 'States of America for governmentalpurposes without the payment of any royaltiesthereon or therefor.

.What'is elairnedis:

l. in arrexploderfor a torpedo, detonating'means com prising-part eta-powder train forignit'ing a main explo- 12 sive charge, mechanical armingmeans for the powder train including a rotary ,Shutter adapted to be set into operative position preliminarily to the ignition of the detonating meansto transmit the flame to the main explosive charge upon ignition of the detonating means, said shutter having a cut-away portion defining a vent, a. housing. having a recess for the shutter, shutter retainer means secured to the housing but being smaller than the recess .to provide an external outlet for said flame to divert it through said vent from said main explosive chargein the event of premature ignition of the detonating means.

2. In an exploder for an underwater torpedo, mechanical arming means insideof the exploder and including a shutter shaft, an impeller outside of the exploder being inherently rapidly rotatable at light torque by movement otthe torpedo relative to the water in which it is immersed, a step -down gear train for driving the arming means fromthe impeller at a low rate and heavy torque, an adjustable stufiing box for excluding water from the arming means and a gear case open to the water, said gear casecontaining the gear train and including a portion for carrying thestutiing box to surround the shutter shaft so that variations in the adjustment of the stuffing box will be least likely to impose ,a brake on the motion of the arming means.

3. In-anexploder for an underwater torpedo, mechanical arming meansconsisting of a shutter shaft and shutter movable to a flame-transmitting position of the shutter for the ignition of a main explosive charge, a casing secludingthe arming means from surrounding seawater, a prime mover for the arming means exposed to the seawater and. revoluble athigh speed but with a light torque by the progressof the torpedo through the water at least for the period of a safety run, and means for preventing an unpredicable increasein said safety run, said means involving a step-down gear drive also exposed to the seawater, being coupled between the exposed prime mover .and thesecluded arming means for driving the latter at a low rate but with a heavy torque, said means including an adjustable-stufiing box for the shutter shaft at its entranceinto the casing, the adjustments of which stufiingbox are least like to brake the arming means because of fitting in where the torque is heaviest.

4. Ina power-driven underwater torpedo, an exploder having an impeller rapidly revoluble at light torque, mechanicalarming means-slowly revoluble at heavy torque,

\ a gear train couplingthe. impeller with the arming means and being exposed to the water in common with the impeller, and an adjustable stufilng box for excluding the waterfront .the inside of the exploder, fitting around a revolving part of the armingmeans at a place closely adjacent thereto so that its ,adjustmentswill be least likely to affect the rate of revolutionv of the arming means.

5. In an underwater torpedo, revoluble mechanical arming-means including an impeller driven shaft, a hub in whichthe shaft has bearing, means for preventing revolutionpf theimpeller and driving of the arming means immediately prior to. launching, said means consisting of a safety arming .Wire thrust through the hub and the shaft and adapted to be externally anchored, and a.-friction grip device located in the hub, bearing on the arming wire to. prevent its.accidental dislodgement from said revoluble shaft.

6. 'In an underwatertorpedo, an exploder having a revoluble impeller, mechanical arming means drivable by theimpellerto a position of flame transfer-to ,a,main,explosive charge, asafety arming wire adaptedto have one of itsends anchored externallyof the torpedo and to have its other end applied to a revoluble part of the impeller to prevent its revolution, a friction grip device adapted to bear on the arming Wire to prevent accidental dislodgement, and means obstructing the friction grip device but being withdrawahle immediately ,prior to the launching of the torpe'doflto releasethe gripdevice.

'7. In an underwater torpedo, an exploder having a rev- 13 oluble impeller, mechanical arming means drivable by the mpeller to a position of flame transfer to a main exploslve charge, an externally anchored safety arming wire inserted in the exploder and applied to a revoluble part of the impeller whence it is again separable by the launch ing of the torpedo, a spring-actuated grip device adapted to bear on the arming wire, and obstructing means initially in front of said device to hold it off the wire, but being withdrawable immediately prior to said launching.

8. In a missile adapted to be projected through a fluid medium, instrumentalities within the missile operating as a register of the distance traveled by the missile, a fluidimpelled member carried by the missile revolved by the impact of the fluid there-against to actuate said instru mentalities until a set distance is traveled, and locking means functioning through the end thrust of the fluid on said fluid-impelled member when said distance has been traveled to lock said instrumentalities against further actuation.

9. In a torpedo exploder, an impeller having a shaft revolving under an end thrust, arming means driven by said impeller shaft for arming the exploder, a slotted gear serving as a thrust bearing for the impeller shaft, and means for rotating the slotted gear from the impeller shaft until the exploder is armed,.whereupon the slot comes into registry with the end of the impeller shaft and the shaft is forced by the impeller end thrust through the slot out of driving engagement with rotating means but into locking engagement therewith.

10. In a torpedo exploder, mechanical arming means including a rotary shutter adapted to be moved to a flametransmitting position, a shaft on which the shutter is fixed, an impeller having a gear train coupled with said shaft for moving the shutter, an open electrical arming switch, and a cam on the shaft controlling the switch, said cam moving with the shaft and shutter and causing the closure of the arming switch substantially with the arrival of the shutter at the flame-transmitting position.

11. In a torpedo exploder, a rotary arming shutter, an impeller having a worm-shaft revolving under an end thrust, a gear train having a wormwheel in mesh with the worm on the shaft for driving the gear train, and a gear driving the shutter to an arming position, said gear being driven by said train and serving as a thrust bearing for the impeller shaft, said gear having a slot into which the end of the shaft is impelled by the end thrust, causing unmeshing of the worm from the wormwheel and locking of both the gear train and the arming shutter.

12. In an underwater torpedo, an exploder having a rotary arming shutter adapted to be moved to a flametransmitting position, a gear train to drive said shutter to that position, a fluid-actuated impeller having a shaft to drive the gear train and revolving under the end thrust of the impeller, and a settable gear which is part of the gear train and forms a thrust bearing for the shaft, said gear being connected with the shutter and having a slot reg istrable with the shaft end, said gear being marked with indicia enabling the initial distancing of the slot from the shaft end by setting the gear and the determination of the period required to elapse before the shaft is impelled into the slot by said end thrust.

13. In a torpedo exploder, a rotary arming shutter, an impeller having worm-shaft revolving under an end thrust, a gear train having a worm-wheel in mesh with the worm on the shaft for driving the gear train, means embodied in the gear train imposing a frictional drag on the wormwheel thus augmenting the end thrust of the worm-shaft, and a gear driving the shutter to an arming position, said gear being driven by said train and serving as a thrust bearing for the impeller shaft, said gear having a slot into which the end of the shaft is impelled by the total end thrust imposed thereon, causing unmeshing of the worm from the wormwheel and locking of both the gear train and the arming shutter.

14. In a torpedo adapted to be launched from a submerged submarine vessel, an exploder for the torpedo, nstrumentalities in the exploder determining the launch mg depth and above which it is not intended to cause the vessel to ascend until the torpedo has completed its run toward the target, said instrumentalities consisting of an electrical hydrostatic switch held open at launching by the water pressure at said depth, an electrical circuit held open by said switch and containing detonating means, mechanical arming means actuated by the motion of the torpedo toward the target, said means including a shutter which is slowly moved by said arming means to a flametransmitting position thus establishing a safety period in said torpedo run, and a firing switch in said circuit which is actuated by the impact of the torpedo with the target to close the circuit and ignite the detonating means.

15. In a torpedo, an exploder therefor having means for firing the main explosive charge of the torpedo, said means including an electrical switch and a firing circuit controlled thereby, a piston holding the switch open, an inertia element having a base and carrying the piston, an abutment confronting said element, and a spring holding said element in balanced position by pressing its base against said abutment, said element responding with a wobble action of the base on the abutment upon yielding to the inertia of said element when the torpedo is decelerated in any direction, thus to displace the piston and enable closure of the switch.

16. In a torpedo exploder, a revoluble discardable impeller, means retaining the impeller on the exploder for revolution, mechanical arming means including a gear train driven by the impeller, and means which is a part of the gear train gradually advancing the retaining means to a position whereat the impeller is free to be discarded.

17. In a torpedo exploder, a revoluble discardableimpeller, means retaining the impeller on the exploder for revolution, mechanical arming means including a gear train driven by the impeller, means which is a part of the gear train gradually advancing the retaining means to a position whereat the impeller is free to be discarded, and means imposing a constant expelling pressure on the impeller during said revolution and acting to discard the impeller when the retaining means arrives at said position.

18. In a torpedo exploder, a discardable impeller having a revoluble shaft, retaining means with which the shaft has inter-engagement to retain the impeller on the exploder for revolution, mechanical arming means including a gear train driven by the impeller, means which is part of the gear train gradually advancing the retaining means to a position of disengagement from the shaft, and a spring and a member which is pressed by the spring against the impeller shaft to then eject the shaft to discard the impeller from the exploder and simultaneously lock the gear train.

19. In a torpedo exploder, a discardable impeller having a revoluble shaft with a groove forming a neck, a slide guided transversely of the shaft, having a slot the size of the groove and an end opening the size of the shaft, mechanical arming means including a gear train driven by the impeller and including a gear for gradually advancing the slide to ride the slot on the neck until the opening registers with the shaft, and means imposing a constant expelling pressure on the end of the impeller shaft, said means including an identically diametered portion bearing on the shaft end and upon registration pushing the shaft through the opening to discard the impeller and replace the shaft end to lock the gear train.

20. In a torpedo exploder, a discardable impeller having a revoluble shaft with a groove, a transversely guided slide having a slot fitting the groove to retain the shaft and having an end opening the size of the shaft, and an arming gear train driven by the shaft, said gear train including a gear for gradually advancing the slide until the opening registers with the shaft, one of the gears of said 15 train overlapping the slide --t o :hold it to its transverse guidance.

21'. In a torpedo exploder, a discarda-ble impeller having-a-revoluble-shaft with a pinion, an arming gear train driven by the pinion, a slide retaining the impeller shaft anditspinion in mesh with the gear-train to insure the activity of the gear train, said slide beingslowly advanced by the gear train toward a shaft releasing position during an arming'period, and means to-pushthe impeller shaft to disengage the pinion from the gear train at'the same timeto lockthe slide againsta further advance and the gear train against further activity.

22. In a torpedo exploder, a discardable-impeller having-a shaft with an endcollar, a transversely guided rackedgedslidc which is slotted-to let the shaft through, said slide obstructing the collar'and' having an opening ending the-slot, means pushingon-the collar tending to eject the shaft, an arming gear-train driven by the shaft-to establish an arming period, and means-to set the duration of the arming period, said means consisting of a spring biased axially movable shaft havinga-pinion inconstant mesh with the rack, and having a-gear' inmeshwith and forming part of the gear-train, and'a wrench .end on said axially movable shaft adapted to receive a wrench for an axial pus-h on said shaft to momentarily disengage its gear from the train and a turn to-rnovethe slide .for a chosen distance of the opening for access 'by the pushing means.

'23. In an exploder for an underwater torpedo,.an arming gear train for moving an arming shutter to a flametransmitting position, an impeller operable by the passage of the torpedo through a body of water to actuate said gear train, and means embodied in the gear train, imposing a brake on its actuation until the torpedo has reached a predetermined linear speed.

24. :In an exploder'for .an underwater torpedo, an arming geartrain for moving -an arming shutter to'a flametransmitting position, an impeller operable by thepassage of the torpedo through a body of water to actuate said gear trai-n,'-a sh-aft included in said geartrain and having a cam, and a spring-biased yoke straddling the cam, obstructing the cam to impose a brake on the gear train until the torpedo has reached a predetermined linear speed.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Rad o Pr xi i y ,FuseDQsi n by Hin an, J et at, pages 12 and 1 3. National Bureau of Standard Journal of Research, volume 37, July 1946, Research Paper RIB-1723. 

